fix(template): enable Widevine DRM in the shipped chromium

Stock nixpkgs chromium has no Widevine CDM, so DRM streams (Netflix,
Spotify web player) fail out of the box. Override with
enableWideVine = true — allowUnfree is already on in the template,
and the wrapper pulls the prebuilt CDM (~no rebuild, binary-cached
chromium plus the -wv variant). Verified live on TuringMachine
(downstream flake updated the same way, CDM present in the wrapper).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

templates/downstream/home.nix

@@ -91,7 +91,9 @@
   home.packages = with pkgs; [
     libreoffice-fresh   # office suite (documents, sheets, slides)
     vscode              # code editor (unfree; allowUnfree is on)
-    chromium            # web browser (mime defaults → chromium-browser.desktop)
+    (chromium.override { enableWideVine = true; })
+                        # web browser with Widevine DRM (Netflix, Spotify web…);
+                        # unfree CDM — mime defaults → chromium-browser.desktop
     gimp                # raster image editor
     inkscape            # vector graphics
     mpv                 # media player